title: SARS coronavirus: unusual lability of the nucleocapsid protein.
abstract: The severe acute respiratory syndrome (SARS) is a contagious disease that killed hundreds and sickened thousands of people worldwide between November 2002 and July 2003. The nucleocapsid (N) protein of the coronavirus responsible for this disease plays a critical role in viral assembly and maturation and is of particular interest because of its potential as an antiviral target or vaccine candidate. Refolding of SARS N-protein during production and purification showed the presence of two additional protein bands by SDS-PAGE. Mass spectroscopy (MALDI, SELDI, and LC/MS) confirmed that the bands are proteolytic products of N-protein and the cleavage sites are four SR motifs in the serine-arginine-rich region-sites not suggestive of any known protease. Furthermore, results of subsequent testing for contaminating protease(s) were negative: cleavage appears to be due to inherent instability and/or autolysis. The importance of N-protein proteolysis to viral life cycle and thus to possible treatment directions are discussed.
authors.affiliation: Centre for Biologics Research, Biologics and Genetic Therapies Directorate, Health Canada, 251 Sir Frederick Banting Driveway, AL:2201E, Ottawa, Ont., Canada K1A 0L2.
authors.forename: John
authors.initials: J
authors.lastname: Mark
authors.affiliation: Centre for Biologics Research, Biologics and Genetic Therapies Directorate, Health Canada, 251 Sir Frederick Banting Driveway, AL:2201E, Ottawa, Ont., Canada K1A 0L2.
authors.forename: Xuguang
authors.initials: X
authors.lastname: Li
authors.affiliation: Centre for Biologics Research, Biologics and Genetic Therapies Directorate, Health Canada, 251 Sir Frederick Banting Driveway, AL:2201E, Ottawa, Ont., Canada K1A 0L2.
authors.forename: Terry
authors.initials: T
authors.lastname: Cyr
authors.affiliation: Centre for Biologics Research, Biologics and Genetic Therapies Directorate, Health Canada, 251 Sir Frederick Banting Driveway, AL:2201E, Ottawa, Ont., Canada K1A 0L2.
authors.forename: Sylvie
authors.initials: S
authors.lastname: Fournier
authors.affiliation: Centre for Biologics Research, Biologics and Genetic Therapies Directorate, Health Canada, 251 Sir Frederick Banting Driveway, AL:2201E, Ottawa, Ont., Canada K1A 0L2.
authors.forename: Bozena
authors.initials: B
authors.lastname: Jaentschke
authors.affiliation: Centre for Biologics Research, Biologics and Genetic Therapies Directorate, Health Canada, 251 Sir Frederick Banting Driveway, AL:2201E, Ottawa, Ont., Canada K1A 0L2. Electronic address: Mary_Hefford@hc-sc.gc.ca.
authors.forename: Mary Alice
authors.initials: MA
authors.lastname: Hefford
mesh_terms: D002853:Chromatography, Liquid; D000086462:Coronavirus Nucleocapsid Proteins; D004591:Electrophoresis, Polyacrylamide Gel; D019590:Nucleocapsid Proteins / Q000096:biosynthesis / Q000737:chemistry* / Q000302:isolation & purification; D010446:Peptide Fragments / Q000737:chemistry* / Q000378:metabolism; D010447:Peptide Hydrolases / Q000737:chemistry / Q000378:metabolism; D017510:Protein Folding; D045473:Severe acute respiratory syndrome-related coronavirus / Q000378:metabolism*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
chemical_list: D000086462:Coronavirus Nucleocapsid Proteins; D019590:Nucleocapsid Proteins; D010446:Peptide Fragments; D010447:Peptide Hydrolases